The present invention relates to a power transmission system, a power transmission/communication system, a reader and/or writer and an IC card, wherein proximity radio operating power is transmitted between them and proximity radio cards such as a cash card, a credit card, a railway ticket, a commutation ticket, a coupon ticket, a management card, an ID card, a license, etc. employed in, for example, a cash dispenser, electronic money, an automatic checking and collecting system, a room in/out management system, etc., and communications are carried out therebetween.
It has heretofore been known in Japanese Patent Application Laid-Open Nos. Hei 7-85233 and 9-62816 that power is supplied to a proximity radio card (IC card) from a power supply side in noncontact with the card by using light or magnetic fields.
Japanese Patent Laid-open No. Hei 7-220123 also describes a noncontact type checking and collecting machine intended to reduce power consumption. In this machine, when a human/medium enters a specific output region and a wicket position sensor is turned ON, power is transmitted to the human/medium. In this case, if there is no communication with the human/medium side after an elapse of a specific time, the human/medium at the wicket is judged as a passenger having no noncontact card and transmission of the power is stopped. On the contrary, if there is communication with a noncontact card after an elapse of the specific time since transmission of the power, the human/medium at the wicket is judged as a fair passenger and transmission of the power is kept, and then, after an elapse of a specific time, it is judged that communication with the noncontact card is completed and transmission of the power is stopped.
In a noncontact card system (proximity radio card system) wherein when cash cards, credit cards, railway tickets, commutation tickets, etc. to be used at wickets in railway stations or on buses or at entrances and exits or the like are brought into IC cards, and when a user causes his/her IC card to pass through a reader and/or writer provided at a wicket in a railway station or on a bus or at an entrance and exit or the like in noncontact with the reader and/or writer, a power transmitting wave or a communication wave is radiated from a coil or an antenna of the reader and/or writer and the electromagnetic wave is received and induced by a coil or an antenna provided on the card side to thereby operate circuits on the card side, whereby a signal is detected, the power transmitting wave radiated from the coil or antenna of the reader and/or writer needs to satisfy the radio protection standard.
Meanwhile, the power transmitting wave is defined as the mean value of arbitrary six minutes in consideration of only a thermal effect to a human body by the radio protection standard from the relationship in which it is exposed to the human body and hands.
However, the prior art described in the above document, Japanese Patent Laid-open No. Hei 7-220123 is so configured that when a human/medium enters a specific output region and a wicket position sensor is turned ON, power is transmitted to the human/medium, and in this case, if there is communication with a noncontact card after an elapse of the specific time, the human/medium at the wicket is judged as a fair passenger and transmission of the power is kept, and then, after an elapse of a specific time, it is judged that communication with the noncontact card is completed and transmission of the power is stopped, and consequently, the above specific time has been required to be longer for certainly completing transmission of the power after the elapse of the specific time, and also the transmitted amount of the power has been required to be large for certainly transmitting the power to a noncontact card.
Accordingly, the above prior art has not taken into consideration a point of view that a power transmitting wave radiated from a coil or antenna of a reader and/or writer is required to satisfy the radio protection standard with sufficient allowance by minimizing the transmitted amount of power even during transmission of the power and also minimizing a time required to transmit the power.